Laboratory sampling machine and methods for maintaining chain of custody for samples

A machine and methods for maintaining chain of custody during a sampling procedure is provided, the machine including a sample handling robot having an operation head and a verification head. The verification head can be one of a barcode reader, OCR scanner, of RFID tag reader. The verification head of the machine is adapted to read a sample container prior to sampling an aliquot of liquid, and transferring the aliquot to a testing vial. Each sample container and corresponding testing vial is read prior to performing an operation, such that a chain of custody is properly recorded. The machine can further comprise a lid-opening and closing device adapted for articulating the lid of one or more standard vial types. Additionally, the machine may comprise a manual vial staging area for non-standard vial types. The machine may be further adapted to prepare diluted testing samples or combined reagent samples.